This invention relates to door closing devices and more particularly to devices associated with a door hinge that provide not only a closing force when the door is near the closed position to insure positive door sealing, but also positive detent positions when the door is open at one or more predetermined angles.
In the case of household refrigerators and freezers, it has been the practice of providing positive door closers on certain models such as side-by-side units because of problems of insuring positive door closing on these models. Present refrigerator designs, for reasons of safety, utilize a magnetic rubber gasket to hold the door closed without the use of any mechanical look or latch. While these gaskets hold the door tightly closed, they can provide this force only when the door is actually in the closed position. If the door does not reach the position where the magnetic force can pull the door fully closed, it will remain slightly open allowing the cold air to escape. If this happens there is the danger that the interior will warm excessively as well as cause high energy use to run the refrigerating system.
While some closing force can be obtained by tilting the top of the refrigerator to the rear, it has been found particularly necessary to provide additional closing forces on side-by-side models because the doors have relatively low closing inertia even when the internal door shelves are full, because the doors tend to be quite narrow for a given size. Because of the closing force, it has also been desirable to provide detent positions when the door is open at, for example, at 90 and 150 degree positions. Because an external closer would interfere with access to the refrigerator as well as be vulnerable to damage, it has been recognized that the closer mechanism must be relatively hidden and therefore built into the door hinges.
One type of closer has utilized the weight of the door to provide the closing force. As shown in U.S. Pat. No. 3,628,845, granted Dec. 21, 1971, the lower hinge plate has a fixed bearing member around the hinge pin that has a number of recesses and projections on its upper surface which are engaged by mating projections and recesses on the lower surface of the upper bearing member which is fixed to the door. Thus as the door is opened and closed, the two bearing members act as a cam and cam follower under the biasing force of the weight of the door to produce rotating forces tending to rotate the door in one direction or the other. This arrangement requires that the door move vertically to provide the rotating force which then varies with the contents of the door shelves. Furthermore, the bearing members tend to collect dirt which may affect the operation of the bearings as well as excessive wear.
Another type of door closer is that shown in U.S. Pat. No. 3,452,387 granted Jul. 1, 1969, which is particularly adapted to be mounted entirely within the door adjacent to the upper hinge. The unit includes a rotatable radial cam journaled in one end of the housing and adapted to receive a splined hinge pin secured to the hinge bracket on the refrigerator cabinet. The radial cam works with a spring-loaded roller to provide a biasing force on the cam and provide not only detents for open door positions, but also a closing force when the door is near the closed position. This unit is relatively expensive and difficult to repair and replace, and is therefore been used only in doors that have movable fiberglass insulation.